Majimoji Rurumo

A high-school boy named Shibaki is unpopular with girls due to his reputation for being overly interested in them. After finding a book on summoning witches in the library, he jokingly tries it out, and an apprentice witch named Rurumo appears to grant his wish. She later refuses to take his soul, which results in her being demoted to an apprentice demon. At the start of the story, Rurumo reappears after Shibaki expresses a desire to see her again. She now requires him to use 666 magic tickets that grant wishes in order for her to become a witch again. However, each ticket use shortens Shibaki's life, with his death occurring once all tickets are used. Shibaki is aware of this due to a contract with Rurumo’s familiar, a black cat named Chiro. He must decide whether to help Rurumo or try to save his own life.